Chemical mechanical polishing method for tungsten using polyglycols and polyglycol derivatives

ABSTRACT

A process for chemical mechanical polishing a substrate containing tungsten is disclosed to reduce corrosion rate and inhibit dishing of the tungsten and erosion of underlying dielectrics. The process includes providing a substrate; providing a polishing composition, containing, as initial components: water; an oxidizing agent; a polyglycol or polyglycol derivative; a dicarboxylic acid, a source of iron ions; a colloidal silica abrasive; and, optionally a pH adjusting agent; providing a chemical mechanical polishing pad, having a polishing surface; creating dynamic contact at an interface between the polishing pad and the substrate; and dispensing the polishing composition onto the polishing surface at or near the interface between the polishing pad and the substrate; wherein some of the tungsten (W) is polished away from the substrate, corrosion rate is reduced, dishing of the tungsten (W) is inhibited as well as erosion of dielectrics underlying the tungsten (W).

FIELD OF THE INVENTION

The present invention is directed to the field of chemical mechanicalpolishing of tungsten to inhibit dishing of the tungsten in combinationwith inhibiting erosion of underlying dielectrics and to reducecorrosion rate using a polyglycol or polyglycol derivative. Morespecifically, the present invention is directed to a method for chemicalmechanical polishing of tungsten to inhibit dishing of the tungsten incombination with inhibiting erosion of underlying dielectrics and toreduce corrosion rate by providing a substrate containing tungsten;providing a polishing composition, containing, as initial components:water; an oxidizing agent; a polyglycol or polyglycol derivative; adicarboxylic acid, a source of iron ions; a colloidal silica abrasive;and, optionally a pH adjusting agent; providing a chemical mechanicalpolishing pad, having a polishing surface; creating dynamic contact atan interface between the polishing pad and the substrate; and dispensingthe polishing composition onto the polishing surface at or near theinterface between the polishing pad and the substrate where some of thetungsten is polished away from the substrate.

BACKGROUND OF THE INVENTION

In the fabrication of integrated circuits and other electronic devices,multiple layers of conducting, semiconducting and dielectric materialsare deposited on or removed from a surface of a semiconductor wafer.Thin layers of conducting, semiconducting, and dielectric materials maybe deposited by a number of deposition techniques. Common depositiontechniques in modern processing include physical vapor deposition (PVD),also known as sputtering, chemical vapor deposition (CVD),plasma-enhanced chemical vapor deposition (PECVD), and electrochemicalplating (ECP).

As layers of materials are sequentially deposited and removed, theuppermost surface of the wafer becomes non-planar. Because subsequentsemiconductor processing (e.g., metallization) requires the wafer tohave a flat surface, the wafer needs to be planarized. Planarization isuseful in removing undesired surface topography and surface defects,such as rough surfaces, agglomerated materials, crystal lattice damage,scratches, and contaminated layers or materials.

Chemical mechanical planarization, or chemical mechanical polishing(CMP), is a common technique used to planarize substrates, such assemiconductor wafers. In conventional CMP, a wafer is mounted on acarrier assembly and positioned in contact with a polishing pad in a CMPapparatus. The carrier assembly provides a controllable pressure to thewafer, pressing it against the polishing pad. The pad is moved (e.g.,rotated) relative to the wafer by an external driving force.Simultaneously therewith, a polishing composition (“slurry”) or otherpolishing solution is provided between the wafer and the polishing pad.Thus, the wafer surface is polished and made planar by the chemical andmechanical action of the pad surface and slurry.

Substrates in the electronics industry possess a high degree ofintegration where semiconductor bases include multilayers ofinterconnected structures. The layers and the structures include a widevariety of materials such as single crystal silicon, polycrystallinesilicon, tetraethyl orthosilicate, silicon dioxide, silicon nitride,tungsten, titanium, titanium nitride and various other conductive,semiconductive and dielectric materials. Because these substratesrequire various processing steps, including CMP to form a finalmultilayered interconnected structure, it is often highly desirable toutilize polishing compositions and processes that are selective forspecific materials depending on the intended applications.Unfortunately, such polishing compositions can cause excessive dishingof the conductive material which can lead to erosion of dielectricmaterial. The topographical defects which can result from such dishingand erosion can further lead to non-uniform removal of additionalmaterials from the substrate surface, such as barrier layer materialdisposed beneath the conductive material or dielectric material andproduce a substrate surface having less than desirable quality which cannegatively impact the performance of the integrated circuit.

Chemical mechanical polishing has become a preferred method forpolishing tungsten during the formation of tungsten interconnects andcontact plugs in integrated circuit designs. Tungsten is frequently usedin integrated circuit designs for contact/via plugs. Typically, acontact or via hole is formed through a dielectric layer on a substrateto expose regions of an underlying component, for example, a first levelmetallization or interconnect. Unfortunately, many CMP slurries used topolish tungsten cause the problem of dishing. The severity of thedishing can vary but it typically is severe enough to cause erosion ofunderlying dielectric materials such as TEOS.

Another problem associated with polishing metals such as tungsten iscorrosion. The corrosion of metals is a common side-effect of CMP.During the CMP process the metal polishing slurry that remains on thesurface of the substrate continues to corrode the substrate beyond theeffects of the CMP. Sometimes corrosion is desired; however, in mostsemiconductor processes corrosion is to be reduced or inhibited.Corrosion may also contribute to surface defects such as pitting andkey-holing. These surface defects significantly affect the finalproperties of the semiconductor device and hamper its usefulness.Therefore, there is a need for a CMP polishing method and compositionfor tungsten which inhibits dishing of tungsten and erosion ofunderlying dielectric materials such as TEOS and also reduces corrosionrate.

SUMMARY OF THE INVENTION

The present invention provides a method of chemical mechanical polishingtungsten, comprising: providing a substrate comprising tungsten and adielectric; providing a chemical mechanical polishing composition,comprising, as initial components: water; an oxidizing agent; apolyglycol or polyglycol derivative in amounts of at least 50 ppm; acolloidal silica abrasive; a dicarboxylic acid or salt thereof; a sourceof iron (III) ions; and, optionally, a pH adjusting agent; providing achemical mechanical polishing pad, having a polishing surface; creatingdynamic contact at an interface between the chemical mechanicalpolishing pad and the substrate; and dispensing the chemical mechanicalpolishing composition onto the polishing surface of the chemicalmechanical polishing pad at or near the interface between the chemicalmechanical polishing pad and the substrate; wherein some of the tungstenis polished away from the substrate.

The present invention provides a chemical mechanical method of polishingtungsten, comprising: providing the substrate comprising tungsten and adielectric; providing a chemical mechanical polishing composition,comprising, as initial components: water; an oxidizing agent; apolyglycol or a polyglycol derivative in amounts of 50 ppm to 1000 ppm;a colloidal silica abrasive; a dicarboxylic acid or salt thereof; asource of iron (III) ions; and, optionally, a pH adjusting agent;providing a chemical mechanical polishing pad, having a polishingsurface; creating dynamic contact at an interface between the chemicalmechanical polishing pad and the substrate; and dispensing the chemicalmechanical polishing composition onto the polishing surface of thechemical mechanical polishing pad at or near the interface between thechemical mechanical polishing pad and the substrate; wherein some of thetungsten is polished away from the substrate; wherein the chemicalmechanical polishing composition provided has a tungsten removal rate of≥1,000 Å/min with a platen speed of 80 revolutions per minute, a carrierspeed of 81 revolutions per minute, a chemical mechanical polishingcomposition flow rate of 125 mL/min, a nominal down force of 21.4 kPa ona 200 mm polishing machine; and, wherein the chemical mechanicalpolishing pad comprises a polyurethane polishing layer containingpolymeric hollow core microparticles and a polyurethane impregnatednon-woven subpad.

The present invention provides a chemical mechanical method of polishingtungsten, comprising: providing a substrate comprising tungsten and adielectric; providing a chemical mechanical polishing composition,comprising, as initial components: water; an oxidizing agent; apolyglycol or polyglycol derivative in an amount of 50 ppm to 800 ppm; acolloidal silica abrasive; malonic acid or salt thereof; a source ofiron (III) ions; and, optionally, a pH adjusting agent; providing achemical mechanical polishing pad, having a polishing surface; creatingdynamic contact at an interface between the chemical mechanicalpolishing pad and the substrate; and dispensing the chemical mechanicalpolishing composition onto the polishing surface of the chemicalmechanical polishing pad at or near the interface between the chemicalmechanical polishing pad and the substrate; wherein some of the tungstenis polished away from the substrate; wherein the chemical mechanicalpolishing composition provided has a tungsten removal rate of ≥1,000Å/min with a platen speed of 80 revolutions per minute, a carrier speedof 81 revolutions per minute, a chemical mechanical polishingcomposition flow rate of 125 mL/min, a nominal down force of 21.4 kPa ona 200 mm polishing machine; wherein the chemical mechanical polishingpad comprises a polyurethane polishing layer containing polymeric hollowcore microparticles and a polyurethane impregnated non-woven subpad.

The present invention provides a method of chemical mechanical polishingtungsten, comprising: providing the substrate comprising tungsten and adielectric; providing a chemical mechanical polishing composition,comprising, as initial components: water; 0.01 to 10 wt % of anoxidizing agent, wherein the oxidizing agent is hydrogen peroxide; 100ppm to 500 ppm of a polyglycol or polyglycol derivative; 0.01 to 10 wt %of a colloidal silica abrasive; 100 to 1,400 ppm malonic acid or saltthereof; 100 to 1,000 ppm of a source of iron (III) ions, wherein thesource of iron (III) ions is ferric nitrate nonahydrate; and,optionally, a pH adjusting agent; wherein the chemical mechanicalpolishing composition has a pH of 1 to 7; providing a chemicalmechanical polishing pad, having a polishing surface; creating dynamiccontact at an interface between the chemical mechanical polishing padand the substrate; and dispensing the chemical mechanical polishingcomposition onto the polishing surface of the chemical mechanicalpolishing pad at or near the interface between the chemical mechanicalpolishing pad and the substrate; wherein some of the tungsten ispolished away from the substrate.

The present invention provides a method of chemical mechanical polishingtungsten, comprising: providing a substrate comprising tungsten and adielectric; providing a chemical mechanical polishing composition,comprising, as initial components: water; 1 to 3 wt % of an oxidizingagent, wherein the oxidizing agent is hydrogen peroxide; 50 to 500 ppmof a polyglycol or polyglycol derivative, 0.2 to 5 wt % of a colloidalsilica abrasive; 120 to 1,350 ppm of malonic acid; 250 to 400 ppm of asource of iron (III) ions, wherein the source of iron (III) ions isferric nitrate nonahydrate; and, optionally, a pH adjusting agent;wherein the chemical mechanical polishing composition has a pH of 2 to3; providing a chemical mechanical polishing pad, having a polishingsurface; creating dynamic contact at an interface between the chemicalmechanical polishing pad and the substrate; and dispensing the chemicalmechanical polishing composition onto the polishing surface of thechemical mechanical polishing pad at or near the interface between thechemical mechanical polishing pad and the substrate; wherein some of thetungsten is polished away from the substrate.

The foregoing methods of the present invention use a chemical mechanicalpolishing composition comprising a polyglycol or polyglycol derivativein certain amounts to polish tungsten and inhibit dishing of thetungsten in combination with inhibiting erosion of underlyingdielectrics. The method also reduces corrosion rate.

DETAILED DESCRIPTION OF THE INVENTION

As used throughout this specification the following abbreviations havethe following meanings, unless the context indicates otherwise: °C.=degrees Centigrade; g=grams; L=liters; mL=milliliters; μ=μm=microns;kPa=kilopascal; Å=angstroms; mV=millivolts; DI=deionized; ppm=parts permillion=mg/L; mm=millimeters; cm=centimeter; min=minute; rpm=revolutionsper minute; lbs=pounds; kg=kilograms; W=tungsten; HO=hydroxyl;PO=propylene oxide; EO=ethylene oxide; PEG=polyethylene glycol;Mw=weight average molecular weight in g/mole; ICP-OES=inductivelycoupled plasma optical emission spectroscopy; PS=polishing slurry;CS=control slurry; wt %=percent by weight; and RR=removal rate.

The term “chemical mechanical polishing” or “CMP” refers to a processwhere a substrate is polished by means of chemical and mechanical forcesalone and is distinguished from electrochemical-mechanical polishing(ECMP) where an electric bias is applied to the substrate. The term“TEOS” means the silicon dioxide formed from tetraethyl orthosilicate(Si(OC₂H₅)₄). The term “polyglycol” means an organic compound havingmore than one ether linkage that yields one or more glycols onhydrolysis of the ether linkages. The term “polyglycol derivative” meansan organic compound derived from a polyglycol where one or more hydrogenatoms of the polyglycol are replaced with an organic functional moiety.The term “alkyl” means an organic group with a general formula:C_(n)H_(2n+1) where “n” is an integer and the “yl” ending means afragment of an alkane formed by removing a hydrogen. The “

” in a formula or moiety indicates a chemical bond. The term “moiety”means a part or a functional group of a molecule. The terms “a” and “an”refer to both the singular and the plural. All percentages are byweight, unless otherwise noted. All numerical ranges are inclusive andcombinable in any order, except where it is logical that such numericalranges are constrained to add up to 100%.

The method of polishing a substrate of the present invention uses achemical mechanical polishing composition containing an oxidizing agent;a polyglycol or a polyglycol derivative in amounts of 50 ppm or greater;a colloidal silica abrasive; a dicarboxylic acid or salt thereof; asource of iron (III) ions; water; and, optionally, a pH adjusting agentto provide for the removal of tungsten from the substrate surface whileinhibiting dishing of the tungsten, erosion of underlying dielectricmaterials and reducing corrosion rate.

Preferably, the polyglycols and polyglycol derivatives of the presentinvention have a general formula:

wherein R₁ is hydrogen or a linear or branched (C₁-C₄)alkyl, preferablyR₁ is hydrogen or (C₁-C₂)alkyl, more preferably R₁ is hydrogen; m and nare integers, wherein m is an integer of 2 to 4, preferably m is 2 to 3,more preferably m is 2, n is an integer of 3 or greater, preferably n isan integer of 3 to 200, more preferably n is an integer of 3 to 150,still more preferably n is an integer of 3 to 100, even more preferablyn is an integer of 3 to 50, and when m is 2, it is preferred that R₁ ishydrogen or (C₁-C₂)alkyl, more preferably R₁ is hydrogen or methyl, mostpreferably R₁ is hydrogen when m is 2; R₂ is hydrogen, or a linear orbranched (C₁-C₂₀)alkyl, or R₂ is a moiety having a formula:

wherein q is an integer of 1 or greater, preferably q is an integer of10 to 20, more preferably q is an integer of 12 to 20, still morepreferably q is an integer of 15 to 16, or R₂ is a moiety having aformula:

wherein R₃ is linear or branched (C₁-C₂₀)alkyl, preferably R₃ is linearor branched (C₁-C₁₅)alkyl, more preferably R₃ is linear or branched(C₂-C₁₀)alkyl, or R₂ is a moiety having a general formula:

wherein R₄ is a fatty acid having from 10 to 20 carbon atoms, preferablyfrom 12 to 18 carbon atoms, more preferably R₄ is lauric acid or oleicacid moiety and still more preferably R₄ is oleic acid moiety, and x, yand z are integers wherein the sum equals 20. Preferably R₂ is hydrogen,or the moiety having formula (II) or the moiety having formula (IV),more preferably R₂ is hydrogen or the moiety having formula (II), evenmore preferably R₂ is hydrogen, or the moiety having formula (II) andwherein q is an integer of 15 to 16, still more preferably R₂ ishydrogen, or the moiety of formula (II) and wherein q is 16, and mostpreferably R₂ is hydrogen.

Preferred polyglycols of the present invention are polyethylene glycolsand polypropylene glycols having weight average molecular weights ing/mole of 150 and greater, preferably 200 and greater, more preferablyfrom 200 to 100,000, still more preferably from 200 to 20,000, even morepreferably from 200 to 10,000 and further still more preferably from 200to 1000. It is most preferred that the polyglycols are polyethyleneglycols having a weight average molecular weight in g/mole of 200 to100,000, more preferably from 200 to 10,000. Preferred polyglycols alsoinclude random EO/PO copolymers with weight average weight molecularweights in g/mole of greater than 1000, preferably greater than 10,000and more preferably greater than 50,000.

Examples of preferred polyglycol derivatives are polyalkylene glycolesters. Examples of preferred polyalkylene glycol esters arepolyethylene glycol monostearate compounds having a general formula:

wherein n is an integer from 10 to 100, preferably from 10 to 50.

Examples of preferred polyglycol derivatives also are polyoxyethylenesorbitan fatty acid esters (polysorbate compounds) wherein R₂ is moiety(IV) above. Examples of such esters are polyoxyethylenesorbitanmonolaurate, polyoxyethylenesorbitan monopalmitate,polyoxyethylenesorbitan monostearate and polyoxyethylenesorbitanmonooleate.

The polyglycol and polyglycol derivatives can be prepared by methodsknown in the art and literature. Many of the polyglycol and polyglycolderivatives can be commercially obtained such as from SIGMA-ALDRICH®.

Optionally, the chemical mechanical polishing compositions of thepresent invention include polystyrenesulfonates or derivatives thereof.Polystyrenesulfonates are compounds which include a moiety in theirstructure having a general formula:

wherein t is an integer of 2 or greater and Y⁺ is H⁺ or an alkali metalion such as Na⁺ or K⁺. A preferred example of a polystyrene sulfonatederivative is poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate).Preferably polystyrene sulfonates and derivatives thereof are includedin chemical mechanical polishing compositions containing polyethyleneglycols. Preferably the polystyrene sulfonates and derivatives thereofare included in chemical mechanical polishing compositions of thepresent invention wherein the chemical mechanical polishing compositionsinclude polyethylene glycols and colloidal silica abrasives having a (−)zeta potential. Preferably the polystyrene sulfonates and polystyrenesulfonate derivatives are included in amounts of 100 ppm or greater,more preferably from 100 ppm to 3000 ppm, even more preferably from 200ppm to 2500 ppm.

Preferably, the method of polishing a substrate of the presentinvention, comprises: providing the substrate, wherein the substratecomprises tungsten and a dielectric; providing a chemical mechanicalpolishing composition, comprising, preferably, consisting of, as initialcomponents: water; an oxidizing agent, preferably in amounts of at least0.01 wt % to 10 wt %, more preferably in amounts of 0.1 wt % to 5 wt %,still more preferably from 1 wt % to 3 wt %; a polyglycol or polyglycolderivative in amounts of at least 50 ppm, preferably 50 ppm to 1000 ppm,more preferably from 50 ppm to 800 ppm, even more preferably from 100ppm to 500 ppm; a colloidal silica abrasive having a positive ornegative zeta potential, preferably in amounts of 0.01 wt % to 10 wt %,more preferably from 0.05 wt % to 7.5 wt %, even more preferably from0.1 wt % to 5 wt %, still more preferably from 0.2 wt % to 5 wt %, mostpreferably from 0.2 wt % to 2 wt %; a dicarboxylic acid, salt thereof ormixtures thereof, preferably in amounts of 100 ppm to 1400 ppm, morepreferably from 120 ppm to 1350 ppm; a source of iron (III) ions,preferably, wherein the source of iron (III) ions is ferric nitratenonahydrate; and, optionally, a pH adjusting agent; preferably, whereinthe chemical mechanical polishing composition has a pH of 1 to 7; morepreferably, of 1.5 to 4.5; still more preferably, 1.5 to 3.5; still evenmore preferably, of 2 to 3, most preferably, of 2 to 2.5; providing achemical mechanical polishing pad, having a polishing surface; creatingdynamic contact at an interface between the chemical mechanicalpolishing pad and the substrate; and dispensing the chemical mechanicalpolishing composition onto the polishing surface of the chemicalmechanical polishing pad at or near the interface between the chemicalmechanical polishing pad and the substrate; wherein at least some of thetungsten is polished away from the substrate.

Preferably, in the method of polishing a substrate of the presentinvention, the substrate comprises tungsten and a dielectric. Morepreferably, the substrate provided is a semiconductor substratecomprising tungsten and a dielectric. Most preferably, the substrateprovided is a semiconductor substrate comprising tungsten depositedwithin at least one of holes and trenches formed in a dielectric such asTEOS. Preferably the substrate is free of nickel phosphorous.

Preferably, in the method of polishing a substrate of the presentinvention, the water contained, as an initial component, in the chemicalmechanical polishing composition provided is at least one of deionizedand distilled to limit incidental impurities.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, an oxidizing agent, wherein theoxidizing agent is selected from the group consisting of hydrogenperoxide (H₂O₂), monopersulfates, iodates, magnesium perphthalate,peracetic acid and other per-acids, persulfate, bromates, perbromate,persulfate, peracetic acid, periodate, nitrates, iron salts, ceriumsalts, Mn (III), Mn (IV) and Mn (VI) salts, silver salts, copper salts,chromium salts, cobalt salts, halogens, hypochlorites and a mixturethereof. More preferably, the oxidizing agent is selected from hydrogenperoxide, perchlorate, perbromate; periodate, persulfate and peraceticacid. Most preferably, the oxidizing agent is hydrogen peroxide.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, 0.01 to 10 wt %, more preferably, 0.1to 5 wt %; most preferably, 1 to 3 wt % of an oxidizing agent.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, a source of iron (III) ions. Morepreferably, in the method of the present invention, the chemicalmechanical polishing composition provided contains, as an initialcomponent, a source of iron (III) ions, wherein the source of iron (III)ions is selected from the group consisting iron (III) salts. Mostpreferably, in the method of the present invention, the chemicalmechanical polishing composition provided contains, as an initialcomponent, a source of iron (III) ions, wherein the source of iron (III)ions is ferric nitrate nonahydrate, (Fe(NO₃)₃.9H₂O).

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, a source of iron (III) ionssufficient to introduce 1 to 200 ppm, preferably, 5 to 150 ppm, morepreferably, 7.5 to 125 ppm, most preferably, 10 to 100 ppm of iron (III)ions to the chemical mechanical polishing composition. It isparticularly preferred that the source of iron (III) is included tointroduce 10 to 150 ppm of iron (III) to the chemical mechanicalpolishing composition.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, a source of iron (III) ions. Morepreferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, 100 to 1,000 ppm, preferably, 150 to750 ppm, more preferably, 200 to 500 ppm and most preferably, 250 to 400ppm of a source of iron (III) ions. Most preferably, in the method ofpolishing a substrate of the present invention, the chemical mechanicalpolishing composition provided contains, as an initial component, 100 to1,000 ppm, preferably, 150 to 750 ppm, more preferably, 200 to 500 ppm,most preferably, 250 to 400 ppm of a source of iron (III) ions, whereinthe source of iron (III) ions is ferric nitrate nonahydrate,(Fe(NO₃)₃.9H₂O).

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, a polyglycol or polyglycolderivative. Preferably, in the method of polishing a substrate of thepresent invention, the chemical mechanical polishing compositionprovided contains, as an initial component, at least 50 ppm, preferably50 ppm to 1000 ppm, more preferably from 50 ppm to 800 ppm, even morepreferably from 100 ppm to 500 ppm of a polyglycol or polyglycolderivative.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains a colloidal silica abrasive having a positive or a negativezeta potential. More preferably, in the method of polishing a substrateof the present invention, the chemical mechanical polishing compositionprovided contains a colloidal silica abrasive having a permanentnegative zeta potential, wherein the chemical mechanical polishingcomposition has a pH of 1 to 7, preferably, of 1.5 to 4.5; morepreferably, of 1.5 to 3.5; still more preferably, of 2 to 3, mostpreferably from 2 to 2.5. Still more preferably, in the method ofpolishing a substrate of the present invention, the chemical mechanicalpolishing composition provided contains a colloidal silica abrasivehaving a permanent negative zeta potential, wherein the chemicalmechanical polishing composition has a pH of 1 to 7, preferably, of 1.5to 4.5; more preferably, of 1.5 to 3.5; still more preferably, of 2 to3, most preferably of 2 to 2.5 as indicated by a zeta potential from−0.1 mV to −20 mV.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, a colloidal silica abrasive, whereinthe colloidal silica abrasive has an average particle size ≤100 nm,preferably, 5 to 100 nm; more preferably, 10 to 60 nm; most preferably,20 to 60 nm as measured by dynamic light scattering techniques.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains 0.01 to 10 wt %, preferably 0.05 to 7.5 wt %, more preferably,0.1 to 5 wt %, still more preferably, 0.2 to 5 wt %, most preferably,0.2 to 2 wt % of a colloidal silica abrasive. Preferably the colloidalsilica abrasive has a negative zeta potential.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, a dicarboxylic acid, wherein thedicarboxylic acid includes, but is not limited to malonic acid, oxalicacid, succinic acid, adipic acid, maleic acid, malic acid, glutaricacid, tartaric acid, salts thereof or mixtures thereof. More preferably,in the method of polishing a substrate of the present invention, thechemical mechanical polishing composition provided contains, as aninitial component, a dicarboxylic acid, wherein the dicarboxylic acid isselected from the group consisting of malonic acid, oxalic acid,succinic acid, tartaric acid, salts thereof and mixtures thereof. Stillmore preferably the chemical mechanical polishing composition providedcontains, as an initial component, a dicarboxylic acid, wherein thedicarboxylic acid is selected from the group consisting of malonic acid,oxalic acid, succinic acid, salts thereof and mixtures thereof. Mostpreferably in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, the dicarboxylic acid malonic acid orsalts thereof.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedcontains, as an initial component, 1 to 2,600 ppm, preferably, 100 to1,400 ppm, more preferably, 120 to 1,350 ppm, still more preferably, 130to 1,100 ppm, of a dicarboxylic acid, wherein the dicarboxylic acidincludes, but is not limited to malonic acid, oxalic acid, succinicacid, adipic acid, maleic acid, malic acid, glutaric acid, tartaricacid, salts thereof or mixtures thereof. More preferably, in the methodof polishing a substrate of the present invention, the chemicalmechanical polishing composition provided contains, as an initialcomponent, 1 to 2,600 ppm of malonic acid, salt thereof or mixturesthereof. Most preferably, in the method of polishing a substrate of thepresent invention, the chemical mechanical polishing compositionprovided contains, as an initial component 100 to 1,400 ppm, morepreferably, 120 to 1,350 ppm, still more preferably, 130 to 1,350 ppm,the dicarboxylic acid malonic acid or salts thereof.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition provided has apH of 1 to 7. More preferably, in the method of polishing a substrate ofthe present invention, the chemical mechanical polishing compositionprovided has a pH of 1.5 to 4.5. Still more preferably, in the method ofpolishing a substrate of the present invention, the chemical mechanicalpolishing composition provided has a pH of 1.5 to 3.5. Still even morepreferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition provided has apH of 2 to 3. Most preferably, in the method of polishing a substrate ofthe present invention, the chemical mechanical polishing compositionprovided has a pH of 2 to 2.5.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition providedoptionally contains a pH adjusting agent. Preferably, the pH adjustingagent is selected from the group consisting of inorganic and organic pHadjusting agents. Preferably, the pH adjusting agent is selected fromthe group consisting of inorganic acids and inorganic bases. Morepreferably, the pH adjusting agent is selected from the group consistingof nitric acid and potassium hydroxide. Most preferably, the pHadjusting agent is potassium hydroxide.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing pad provided can by anysuitable polishing pad known in the art. One of ordinary skill in theart knows to select an appropriate chemical mechanical polishing pad foruse in the method of the present invention. More preferably, in themethod of polishing a substrate of the present invention, the chemicalmechanical polishing pad provided is selected from woven and non-wovenpolishing pads. Still more preferably, in the method of polishing asubstrate of the present invention, the chemical mechanical polishingpad provided comprises a polyurethane polishing layer. Most preferably,in the method of polishing a substrate of the present invention, thechemical mechanical polishing pad provided comprises a polyurethanepolishing layer containing polymeric hollow core microparticles and apolyurethane impregnated non-woven subpad. Preferably, the chemicalmechanical polishing pad provided has at least one groove on thepolishing surface.

Preferably, in the method of polishing a substrate of the presentinvention, the chemical mechanical polishing composition provided isdispensed onto a polishing surface of the chemical mechanical polishingpad provided at or near an interface between the chemical mechanicalpolishing pad and the substrate.

Preferably, in the method of polishing a substrate of the presentinvention, dynamic contact is created at the interface between thechemical mechanical polishing pad provided and the substrate with a downforce of 0.69 to 34.5 kPa normal to a surface of the substrate beingpolished.

Preferably, in the method of polishing a substrate of the presentinvention, wherein the chemical mechanical polishing compositionprovided has a tungsten removal rate ≥1,000 Å/min; preferably, ≥1,500Å/min; more preferably, ≥2,000 Å/min. More preferably, in the method ofpolishing a substrate of the present invention, wherein the chemicalmechanical polishing composition provided has a tungsten removal rate of≥1,000 Å/min; preferably, ≥1,500 Å/min; more preferably, ≥2,000 Å/min;and a W/TEOS selectivity of ≥5. Still more preferably, in the method ofpolishing a substrate of the present invention, wherein the tungsten isremoved from the substrate at a removal rate of ≥1,000 Å/min;preferably, ≥1,500 Å/min; more preferably, ≥2,000 Å/min; and a W/TEOSselectivity of 5 to 15. Most preferably, in the method of polishing thesubstrate of the present invention, wherein the tungsten is removed fromthe substrate at a removal rate of ≥1,000 Å/min; preferably, ≥1,500Å/min; more preferably, ≥2,000 Å/min; and a W/TEOS selectivity of 6 to14 and with a platen speed of 80 revolutions per minute, a carrier speedof 81 revolutions per minute, a chemical mechanical polishingcomposition flow rate of 125 mL/min, a nominal down force of 21.4 kPa ona 200 mm polishing machine; and, wherein the chemical mechanicalpolishing pad comprises a polyurethane polishing layer containingpolymeric hollow core microparticles and a polyurethane impregnatednon-woven subpad.

As is illustrated in the following Examples, the polyglycol andpolyglycol derivative CMP methods of the present invention inhibittungsten dishing in combination with inhibiting erosion of underlyingTEOS and further inhibits corrosion rate.

Example 1 Slurry Formulations

The chemical mechanical polishing compositions of this Example wereprepared by combining the components in the amounts listed in Table 1with the balance being DI water and adjusting the pH of the compositionsto the final pH listed in Table 1 with 45 wt % potassium hydroxide.

TABLE 1 Malonic H₂O₂ Slurry Abrasive¹ PEG PEG PSS² Fe(NO₃)₃ Acid (wt #(wt %) (Mw) (ppm) (ppm) (ppm) (ppm) %) pH CS-1 2 — — — 362 137 2 2.3PS-1 2 1000 800 — 362 137 2 2.3 PS-2 2 200 200 — 362 137 2 2.3 PS-3 210,000 200 600 362 137 2 2.3 PS-4 2 10,000 800 2400 362 137 2 2.3 PS-5 21000 200 600 362 137 2 2.3 PS-6 2 1000 800 2400 362 137 2 2.3¹KLEBOSOL ™ 1598-B25 (—) zeta potential abrasive slurry manufactured byAZ Electronics Materials, available from The Dow Chemical Company; and²Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), Mw = 7000available from SIGMA-ALDRICH ®.

Example 2 Corrosion Rate Performance of Polyethylene Glycol CMP Slurries

The corrosion tests were carried out by immersing W blanket wafers (1cm×4 cm) in 15 g slurry samples. The W wafers were removed from testedslurries after 10 min. The solutions were subsequently centrifuged for20 min at 9,000 rpm to remove slurry particles. The supernatant wasanalyzed by ICP-OES to determine the amount of tungsten by weight. Thecorrosion rate (Å/min) was converted from the W mass assuming an etchingwafer surface area of 4 cm². The results of the corrosion tests are inTable 2.

TABLE 2 Slurry # W Corrosion Rate (Å/min) CS-1 25 PS-1 17 PS-2 23 PS-3 5PS-4 9 PS-5 8 PS-6 16

The results of the corrosion rate tests showed that the chemicalmechanical polishing slurries containing the polyethylene glycol and thecombination of the polyethylene glycol and PSS effectively reduced thecorrosion on W containing wafers better than the control slurry (CS-1).

Example 3 Slurry Formulations

The chemical mechanical polishing compositions of this Example wereprepared by combining the components in the amounts listed in Table 3with the balance being DI water and adjusting the pH of the compositionsto the final pH listed in Table 3 with 45 wt % potassium hydroxide.

TABLE 3 PEG³, Mw = Malonic Abrasive¹ 200 Fe(NO₃)₃ Acid H₂O₂ Slurry # (wt%) (ppm) (ppm) (ppm) (wt %) pH CS-2 2 — 362 137 2 2.3 PS-7 2  50 362 1372 2.3 PS-8 2 200 362 137 2 2.3 PS-9 2 400 362 137 2 2.3 PS-10 2 600 362137 2 2.3 ¹KLEBOSOL ™ 1598-B25 (—) zeta potential abrasive slurrymanufactured by AZ Electronics Materials, available from The DowChemical Company; ³Available from SIGMA-ALDRICH ®.

Example 4 Chemical Mechanical Polishing—Dishing and Erosion Performanceof Polyethylene Glycol CMP Slurry

The polishing experiments were performed on 200 mm blanket wafersinstalled on an Applied Materials 200 mm MIRRA® polishing machine. Thepolishing removal rate experiments were performed on 200 mm blanket 15kÅ-thick TEOS sheet wafers plus W, Ti, and TiN blanket wafers availablefrom Silicon Valley Microelectronics. All polishing experiments wereperformed using an IC1010™ polyurethane polishing pad paired with anSP2310 subpad (commercially available from Rohm and Haas ElectronicMaterials CMP Inc.) with a typical down pressure of 21.4 kPa (3.1 psi),a chemical mechanical polishing composition flow rate of 125 mL/min, atable rotation speed of 80 rpm and a carrier rotation speed of 81 rpmunless specified otherwise. A Kinik PDA33A-3 diamond pad conditioner(commercially available from Kinik Company) was used to dress thepolishing pad. The polishing pad was broken in with the conditionerusing a down force of 9.0 lbs (4.1 kg) for 15 minutes and 7.0 lbs (3.2kg) for 15 minutes at 80 rpm (platen)/36 rpm (conditioner). Thepolishing pad was further conditioned ex-situ prior to polishing using adown force of 7 lbs (3.2 kg) for 24 seconds. The TEOS erosion depthswere determined by measuring the film thickness before and afterpolishing using a KLA-Tencor FX200 metrology tool. The W removal anddishing rates were determined using a KLA-Tencor RS100C metrology tool.The wafers had varying standard line width features as shown in Tables4A and 4B. In the tables of this example the numerator refers to W andthe denominator refers to TEOS.

TABLE 4A 100/100 100/100 50/50 50/50 10/10 10/10 μm μm μm μm μm μmSlurry dishing erosion dishing erosion dishing erosion # (Å) (Å) (Å) (Å)(Å) (Å) CS-2 1520 30 1270 29 724 266 PS-7 1100 6 1003 12 577 99 PS-81083 4 1018 12 584 156 PS-9 1373 18 1213 41 666 277 PS-10 1393 17 119752 657 246

TABLE 4B 0.25/0.25 0.25/0.25 7/3 μm 7/3 μm 9/1 μm 9/1 μm μm μm dishingerosion dishing erosion dishing erosion Slurry # (Å) (Å) (Å) (Å) (Å) (Å)CS-2 499 698 450 1143 75 357 PS-7 359 450 269 797 263 246 PS-8 359 415263 762 165 252 PS-9 424 675 354 1140 99 273 PS-10 423 603 347 975 121317

Overall the slurries which included polyethylene glycol showed improvedperformance in inhibiting dishing of the W and reduced erosion of TEOS.

Example 5 W, TEOS Removal Rate and W, TEOS Selectivity

The polishing experiments for W and TEOS removal rates were performedsubstantially as described in Example 4 using the same apparatus andparameters. The wafers were from Silicon Valley Microelectronics. Theresults are in Table 5.

TABLE 5 Slurry # W RR (Å/min) TEOS RR (Å/min) W/TEOS Selectivity CS-21654 188 9 PS-7 1832 215 9 PS-8 1760 209 8 PS-9 1812 184 10 PS-10 1790156 11

The chemical mechanical polishing compositions of the present inventionshowed good W RR of greater than 1700 Å/min and good W/TEOS selectivity.

Example 6 Slurry Formulations

The chemical mechanical polishing compositions of this Example wereprepared by combining the components in the amounts listed in Table 6with the balance being DI water and adjusting the pH of the compositionsto the final pH listed in Table 6 with 45 wt % potassium hydroxide.

TABLE 6 Malonic Abrasive⁴ PEG PEG Fe(NO₃)₃ Acid H₂O₂ Slurry # (wt %)(Mw) (ppm) (ppm) (ppm) (wt %) pH CS-3 0.6 — — 362 137 2 2.3 PS-11 0.6100,000 200 362 137 2 2.3 PS-12 0.6 10,000 200 362 137 2 2.3 PS-13 0.62000 200 362 137 2 2.3 PS-14 0.6 200 200 362 137 2 2.3 PS-15 0.6 200 800362 137 2 2.3 ⁴FUSO HL-3 (+) zeta potential abrasive slurry manufacturedby Fuso Chemical Co., LTD.

Example 7 Corrosion Rate Performance of Polyethylene Glycol CMP Slurries

The corrosion tests were carried out by immersing W blanket wafers (1cm×4 cm) in 15 g slurry samples. The W wafers were removed from testedslurries after 10 min. The solutions were subsequently centrifuged for20 min at 9,000 rpm to remove slurry particles. The supernatant wasanalyzed by ICP-OES to determine the amount of tungsten by weight. Thecorrosion rate (Å/min) was converted from the W mass assuming an etchingwafer surface area of 4 cm². The results of the corrosion tests are inTable 7.

TABLE 7 Slurry # W Corrosion Rate (Å/min) CS-3 52 PS-11 30 PS-12 28PS-13 28 PS-14 39 PS-15 43

The results of the corrosion rate tests showed that the chemicalmechanical polishing slurries containing the polyethylene glycolseffectively reduced the corrosion on W containing wafers better than thecontrol slurry (CS-3).

Example 8 Slurry Formulations

The chemical mechanical polishing compositions of this Example wereprepared by combining the components in the amounts listed in Table 8with the balance being DI water and adjusting the pH of the compositionsto the final pH listed in Table 8 with 45 wt % potassium hydroxide.

TABLE 8 Abra- A- Malonic H₂O₂ Slurry sive⁴ mount Fe(NO₃)₃ Acid (wt # (wt%) Polysorbitan (ppm) (ppm) (ppm) %) pH CS-4 0.6 — — 362 137 2 2.3 PS-160.6 Monolaurate⁵ 200 362 137 2 2.3 PS-17 0.6 Monolaurate⁵ 800 362 137 22.3 PS-18 0.6 Monopalmitate⁶ 200 362 137 2 2.3 PS-19 0.6 Monopalmitate⁶800 362 137 2 2.3 PS-20 0.6 Monostearate⁷ 200 362 137 2 2.3 PS-21 0.6Monostearate⁷ 800 362 137 2 2.3 PS-22 0.6 Monooleate⁸ 200 362 137 2 2.3PS-23 0.6 Monooleate⁸ 800 362 137 2 2.3 ⁴FUSO HL-3 (+) zeta potentialabrasive slurry manufactured by Fuso Chemical Co., LTD. ⁵Mw = 1228; ⁶Mw= 1277; ⁷Mw = 1309; ⁸Mw = 1310

Example 9 Corrosion Rate Performance of Polysorbitan CMP Slurries

The corrosion tests were carried out by immersing W blanket wafers (1cm×4 cm) in 15 g slurry samples. The W wafers were removed from testedslurries after 10 min. The solutions were subsequently centrifuged for20 min at 9,000 rpm to remove slurry particles. The supernatant wasanalyzed by ICP-OES to determine the amount of tungsten by weight. Thecorrosion rate (Å/min) was converted from the W mass assuming an etchingwafer surface area of 4 cm². The results of the corrosion tests are inTable 9.

TABLE 9 Slurry # W Corrosion Rate (Å/min) CS-4 52 PS-16 68 PS-17 38PS-18 32 PS-19 33 PS-20 35 PS-21 39 PS-22 26 PS-23 31

Except for slurry PS-16 the results of the corrosion rate tests showedthat the chemical mechanical polishing slurries containing thepolysorbitans effectively reduced the corrosion on W containing wafersbetter than the control slurry (CS-4).

Example 10 Slurry Formulations

The chemical mechanical polishing compositions of this Example wereprepared by combining the components in the amounts listed in Table 10with the balance being DI water and adjusting the pH of the compositionsto the final pH listed in Table 10 with 45 wt % potassium hydroxide.

TABLE 10 Ma- Slur- Abra- Polyethyl- A- lonic ry sive⁴ eneglycol mountFe(NO₃)₃ Acid H₂O₂ # (wt %) Ester⁹ (ppm) (ppm) (ppm) (wt %) pH CS-5 0.6— — 362 137 2 2.3 PS-24 0.6 Monostearate,  50 362 137 2 2.3 n = 10, q =16 PS-25 0.6 Monostearate, 100 362 137 2 2.3 n = 10, q = 16 PS-26 0.6Monostearate, 200 362 137 2 2.3 n = 10, q = 16 PS-27 0.6 Monostearate, 50 362 137 2 2.3 n = 25, q = 16 PS-28 0.6 Monostearate, 100 362 137 22.3 n = 25, q = 16 PS-29 0.6 Monostearate, 200 362 137 2 2.3 n = 25, q =16 PS-30 0.6 Monostearate,  50 362 137 2 2.3 n = 45, q = 16 PS-31 0.6Monostearate, 100 362 137 2 2.3 n = 45, q = 16 PS-32 0.6 Monostearate,200 362 137 2 2.3 n = 45, q = 16 PS-33 0.6 Monododecyl,  50 362 137 22.3 n = 25, q = 11 PS-34 0.6 Monododecyl 100 362 137 2 2.3 n = 25, q =11 PS-35 0.6 Monododecyl, 200 362 137 2 2.3 n = 25, q = 11 ⁴FUSO HL-3(+) zeta potential abrasive slurry manufactured by Fuso Chemical Co.,LTD. ⁹Polyethyleneglycol ester having general formula: (VII)

wherein n and q are defined in Table 10.

Example 11 Corrosion Rate Performance of Polyethyleneglycol Ester CMPSlurries

The corrosion tests were carried out by immersing W blanket wafers (1cm×4 cm) in 15 g slurry samples. The W wafers were removed from testedslurries after 10 min. The solutions were subsequently centrifuged for20 min at 9,000 rpm to remove slurry particles. The supernatant wasanalyzed by ICP-OES to determine the amount of tungsten by weight. Thecorrosion rate (Å/min) was converted from the W mass assuming an etchingwafer surface area of 4 cm². The results of the corrosion tests are inTable 11.

TABLE 11 Slurry # W Corrosion Rate (Å/min) CS-5 68 PS-24 84 PS-25 44PS-26 47 PS-27 31 PS-28 52 PS-29 62 PS-30 34 PS-31 54 PS-32 58 PS-33 38PS-34 67 PS-35 69

Except for slurries PS-24 and PS-35 the results of the corrosion ratetests showed that the chemical mechanical polishing slurries containingthe polyethyleneglycol esters of formula (V) effectively reduced thecorrosion on W containing wafers better than the control slurry (CS-5).

What is claimed is:
 1. A method of chemical mechanical polishingtungsten, comprising: providing a substrate comprising tungsten and adielectric; providing a chemical mechanical polishing composition,consisting of, as initial components: water; 0.01 to 10 wt % of anoxidizing agent; 50 to 1000 ppm of a polyglycol or polyglycolderivative; 0.01 to 10 wt % of a colloidal silica abrasive having a (−)negative zeta potential; 1 to 2,600 ppm of a dicarboxylic acid; 100 to1,000 ppm of a source of iron (III) ions; optionally, a pH adjustingagent; and, optionally, a polystyrenesulfonate; wherein the chemicalmechanical polishing composition has a pH of 1 to 7; providing achemical mechanical polishing pad, having a polishing surface; creatingdynamic contact at an interface between the chemical mechanicalpolishing pad and the substrate; and dispensing the chemical mechanicalpolishing composition onto the polishing surface of the chemicalmechanical polishing pad at or near the interface between the chemicalmechanical polishing pad and the substrate to remove at least some ofthe tungsten.
 2. The method of claim 1, wherein the chemical mechanicalpolishing composition provided has a tungsten removal rate of ≥1,000Å/min with a platen speed of 80 revolutions per minute, a carrier speedof 81 revolutions per minute, a chemical mechanical polishingcomposition flow rate of 125 mL/min, a nominal down force of 21.4 kPa ona 200 mm polishing machine; and, wherein the chemical mechanicalpolishing pad comprises a polyurethane polishing layer containingpolymeric hollow core microparticles and a polyurethane impregnatednon-woven subpad.
 3. The method of claim 1, wherein the chemicalmechanical polishing composition, provided consists of, as initialcomponents: the water; 0.1 to 5 wt % of the oxidizing agent, wherein theoxidizing agent is hydrogen peroxide; 50 to 800 ppm of the polyglycol orpolyglycol derivative; 0.05 to 7.5 wt % of the colloidal silica abrasivehaving a (−) negative zeta potential; 100 to 1,400 ppm of thedicarboxylic acid; 150 to 750 ppm of the source of iron (III) ions,wherein the source of iron (III) ions is ferric nitrate; optionally, thepH adjusting agent; and, optionally, a polystyrenesulfonate; wherein thechemical mechanical polishing composition has a pH of 1.5 to 4.5.
 4. Themethod of claim 1, wherein the chemical mechanical polishingcomposition, provided consists of, as initial components: the water; 0.1to 3 wt % of the oxidizing agent, wherein the oxidizing agent ishydrogen peroxide; 100 to 500 ppm of the polyglycol or polyglycolderivative; 0.1 to 5 wt % of the colloidal silica abrasive having a (−)negative zeta potential; 120 to 1,350 ppm of the dicarboxylic acid,wherein the dicarboxylic acid is malonic acid; 200 to 500 ppm of thesource of iron (III) ions, wherein the source of iron (III) ions isferric nitrate; optionally, the pH adjusting agent; and, optionally, apolystyrenesulfonate; wherein the chemical mechanical polishingcomposition has a pH of 1.5 to 3.5.